1. Field
Embodiments of the present invention relate to an optical sensing array embedded in a display and a method for operating the same.
2. Related Art
Display devices have become increasingly popular, and are widely used, such as in cell phones, computer monitors, televisions, tablets, etc. These display devices may be any type of display, including an organic light emitting display (OLED), a liquid crystal display (LCD), etc. In particular, display devices including optical sensors have been developed to, for example, detect a user's interaction with the display device (e.g., an interaction with the display device via the user's finger or via use of a stylus), sense ambient light, scan documents, etc.
However, generally speaking, these embedded optical sensors are manufactured to be formed in the same active area as the display emission elements (e.g., at pixels of a pixel area of a display device). Accordingly, the aperture of the optical sensors (i.e., the portion of display area involved in light sensing) is formed at the expense of the display active area that produces, reflects, and/or transmits light to generate images to be seen by the user of the display device. Consequently, it has been difficult to achieve a sufficiently large optical sensor aperture to be effective at sensing light, while concurrently achieving a visibly bright and power-efficient display. Furthermore, as higher-resolution displays are developed, this problem is exacerbated because the portion of the display surface not involved in producing the image or sensing light does not scale equally with the portion of the display surface which does. That is, the inactive area portion generally grows proportionally larger as the dots per area is reduced, thereby reducing the active area available for both the optical sensors and the display emission elements.
Additionally, the conventional optical sensors are not wavelength selective, and are therefore responsive to light signals other than only the light signal(s) from the particular sources of sensing interest, such as the light signals included in noise corresponding to ambient light (i.e., ambient light noise). As a result, excessive signal processing and power are used to extract the signals of sensing interest from the ambient light noise.
Moreover, when address lines are shared by the optical sensors and the display elements, the processes of reading of the sensors and writing of the display elements may not occur concurrently, resulting in inefficient processing within the display device. Alternatively, when a display device employs separate address control lines, mechanisms, and signals for the optical sensors and the display elements, the area of the display surface allocated to the dual addressing functions is increased, thereby taking additional active area from the display elements.
Furthermore, display devices employing conventional optical sensors may cause crosstalk between the display emission elements and the optical sensors. That is, light from the display elements may be undesirably sensed by the optical sensors, causing incorrect optical readings and/or increased processing to extract the signals of sensing interest from the ambient light noise, or from the light emitted by the display elements.